Blood Bane

You choose one creature  within range that has wounded you with an attack (melee, ranged, or spell) within the last round that has caused you to lose more than 2 hp. By invoking the Blood Bane you mystically mark it as your target. The target must succeed on a Constitution Saving Throw or be targeted as your quarry for revenge.  If the target succeeds the Constitution Saving Throw they manage to shake off the effect entirely. On a failure, your  target subtracts 1d4 from any saving throws made against your effects (attacks, spells, or other features) until the spell ends, and you have advantage on any Wisdom (Perception) or Wisdom (Survival) check made to locate your target.

 As long as it remains on the same plane of existence as you, you know the general direction in which your target is located (ie. North, South, East, West of your current location). You do not know how far or close your target is once it has been marked even if you know the general direction. Your target must remain on the same plane of existence for you to maintain your awareness of your target. If the target tries to teleport or planeshift to a different plane of existence while marked with the Blood Bane they must succeed on a constitution saving throw or will take 3d10 necrotic damage as the spell is forcibly dropped. 

If the target drops to 0 hit points the spell ends automatically and cannot be transferred to another creature without recasting the spell. Unless otherwise dispelled, countered, or forcibly dropped due to concentration, the spell lasts for up to 10 minutes.